Thermoacoustic Tomography - Ultrasound Attenuation Artifacts

Thermoacoustic computerized tomography (TCT) is a hybrid imaging technique exploiting the thermoacoustic effect. TCT has many parallels with X-ray CT, including frequency dependent attenuation of the measured signal. However, the nature of these attenuation phenomena is nearly opposite: X-ray beams "harden", whereas ultrasound pulses "soften" An analytic formula for an attenuated TCT pulse generat.ed by a homogeneous spherical inclusion is presented. Resulting artifacts in reconstructed X-ray CT and TCT images are compared and contrasted.